Question

我想要一个机动运输工具的列表，拖车设备的数量在单独的列中列出。我正在使用case语句对不同的设备类型进行分类，但是我得到了多个退货，而不是每个承运人看到一个退货。

我尝试了ROW OVER（）并得到相同的结果。

SELECT C.ECP_CARRIER_IDENT_ID AS ECP_ID, C.CARRIER_NM, C.MC_NB, C.DOT_NB,
(CASE WHEN E.EQUIPMENT_TYPE_CD = 'TR' THEN E.EQUIPMENT_CT END) AS TRACTORS,
(CASE WHEN E.EQUIPMENT_TYPE_CD = 'SV' THEN E.EQUIPMENT_CT END) AS VAN_TRLS,
(CASE WHEN E.EQUIPMENT_TYPE_CD = 'FT' THEN E.EQUIPMENT_CT END) AS FLATBEDS
FROM ECP_CARRIER C
JOIN ECP_CARRIER_EQUIPMENT E ON C.ECP_CARRIER_IDENT_ID = E.ECP_CARRIER_ID
WHERE CERTIFIED_FG = 1
GROUP BY C.ECP_CARRIER_IDENT_ID, C.CARRIER_NM, C.MC_NB, C.DOT_NB,
E.EQUIPMENT_TYPE_CD, E.EQUIPMENT_CT

我希望所有内容都在同一行，但这是我得到的结果

ECP_NB   CARRIER_NM     MC_NB    DOT_NB  TRACTORS VAN_TRLS   FLATBEDS
 1234   Bob's Trucking   606066     66    10               
 1234   Bob's Trucking   606066     66              12

Answer 1

使用聚合函数并修复group by：

SELECT C.ECP_CARRIER_IDENT_ID AS ECP_ID, C.CARRIER_NM, C.MC_NB, C.DOT_NB,
       MAX(CASE WHEN E.EQUIPMENT_TYPE_CD = 'TR' THEN E.EQUIPMENT_CT END) AS TRACTORS,
       MAX(CASE WHEN E.EQUIPMENT_TYPE_CD = 'SV' THEN E.EQUIPMENT_CT END) AS VAN_TRLS,
       MAX(CASE WHEN E.EQUIPMENT_TYPE_CD = 'FT' THEN E.EQUIPMENT_CT END) AS FLATBEDS
FROM ECP_CARRIER C JOIN
     ECP_CARRIER_EQUIPMENT E
     ON C.ECP_CARRIER_IDENT_ID = E.ECP_CARRIER_ID
WHERE CERTIFIED_FG = 1
GROUP BY C.ECP_CARRIER_IDENT_ID, C.CARRIER_NM, C.MC_NB, C.DOT_NB;

GROUP BY中的键组合应定义结果集中所需的每一行。例如，您不需要E.EQUIPMENT_TYPE_CD的单独行，因此它不应位于GROUP BY中。

将案例语句用作数据透视表-DB2 SQL

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